Figure 2. iNOS⁺ cells in the inflamed pulp. (A) LPS application for 6 hrs (n = 3) caused infiltration of many iNOS⁺ cells with heterogeneous morphology into the inflamed coronal pulp. Many ED1⁺ macrophages and OX6⁺ antigen-presenting cells were also present. Saline application instead of LPS (n = 3) did not cause iNOS⁺ cell infiltration. ED1⁺ cells and OX6⁺ cells were observed in the saline-applied pulps, but their number was quite small compared with those in the LPS-applied pulps. Bars in the low- and high-power fields indicate 200 µm and 50 µm, respectively. The upper portions of these images are close to the exposed surface. (B) Double-staining with ED1 and anti-iNOS antibodies reveals that most of the iNOS⁺ cells were also ED1⁺ (closed arrowheads, ED1⁺ macrophages; open arrowheads, iNOS⁺ cells; open arrows, ED1 and iNOS double-positive cells). In contrast, the population of OX6⁺ cells (closed arrowheads) was completely different from the population of iNOS⁺ cells (open arrowheads).